Satellite therapy delivery system for brain neuromodulation

ABSTRACT

Deep brain electrodes are remotely sensed and activated by means of a remote active implantable medical device (AIMD). In a preferred form, a pulse generator is implanted in the pectoral region and includes a hermetic seal through which protrudes a conductive leadwire which provides an external antenna for transmission and reception of radio frequency (RF) pulses. One or more deep brain electrode modules are constructed and placed which can transmit and receive RF energy from the pulse generator. An RF telemetry link is established between the implanted pulse generator and the deep brain electrode assemblies. The satellite modules are configured for generating pacing pulses for a variety of disease conditions, including epileptic seizures, Turrets Syndrome, Parkinson&#39;s Tremor, and a variety of other neurological or brain disorders.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/619,551, filed Nov. 16, 2009 that claims priority from U.S.Provisional Patent Application Ser. No. 61/115,765, filed Nov. 18, 2008.

FIELD OF INVENTION

The control module typically includes telemetry for wirelesslycommunicating with an external programmer or network to permittransmission of patient data which may include, for example, GPS data,current or historical/sensed patient biologic data, or current orhistorical therapy delivery data. This invention relates to systems forbrain neuromodulation electromagnetic therapy delivery. In particular, asatellite therapy delivery system for brain neuromodulation includes acontrol module having an RF transmitter or transceiver, and a remotesatellite brain stimulation and/or sensing (SBS) module having biologicstimulating and/or sensing electrodes, a power source, and an RFreceiver or transceiver for open or closed looped wireless communicationwith the control module.

BACKGROUND OF THE INVENTION

Deep brain stimulation (DBS) electrodes and/or shallow electrodesincluding subcutaneous or sub-dural electrodes are typically connectedto one or more active implantable medical devices (AIMD) which providevarious types of therapeutic pacing pulses for treating a variety ofdisease conditions including, but not limited to, epileptic seizures,Turrets Syndrome, Parkinson's Tremor, and a variety of otherneurological or brain disorders. Typically these therapy deliverysystems involve one or more DBS and/or shallow electrodes that areimplanted into or adjacent to the brain matter (through a skull burrhole) with leadwires tunneled to an implanted hermetically sealedelectronics module that applies the appropriate electrical therapy.Electrodes implanted deeply within the brain can be unipolar, bipolar,quadpolar, or multipolar, having many channels. Additional electrodescan be placed either subcutaneously or subdurally to create amultiplicity of electrical vectors through brain tissue.

By way of example, FIG. 1 is a side view of a human skull with twoquadpolar DBS electrodes 20 and 20″ placed deeply into the brain matter.There are leads 22, 22′ connected to the deep brain electrodes 20, 20′and routed underneath the skin through a tunneling procedure along theback of the patient's head and down along the side of the patient'sneck. In addition to the deep brain electrodes 20 and 20′, there mayalso be subcutaneous or subdural electrodes 24 and 24″ as shown. In thisway, electrical stimulus may be between any of the electrodes orelectrode pairs shown on the DBS electrodes 20 and 20′ or between theDBS electrodes and the subcutaneous/subdural electrodes 24 and 24′, asshown. This gives the physician a number of options in terms ofelectrical vectors for pacing pulses in the brain and for sensingvarious brain waves.

Leads 22 and 22′ can each consist of a number (bundle) of coaxial orbi-filar leadwires. In this case, there are a sufficient number ofleadwires to supply the two DBS quadpolar electrodes 20 and 20′ (totalof eight leadwires) in addition the quadpolar subcutaneous/subduralelectrodes 24 and 24′ (a total of eight more leadwires). Accordingly, inthe illustrated embodiment, there are a total of sixteen leadwires thatare encompassed within the encapsulated leads 22 and 22′.

FIG. 2 is an X-ray tracing of the front view of the pectoral area of thesame patient shown in FIG. 1. Illustrated are two implantable pulsegenerators 26 and 26′, which are typically housed in titanium cans.Since titanium does not show up that well on an X-ray, one can only seethe outline of the titanium can, but can also see the internal circuitboards 28 and 28′ inside the titanium housings very clearly. One canrefer to prior art cardiac pacemakers for a better explanation of whatthese devices look like. One can also see the leads 22 and 22′ whoseproximal ends plug into connector blocks which are part of the implantedpulse generators 26 and 26′, typically in accordance with AAMI Standardsor ISO Standards, such as ISO IS1 or IS4. These leads can also bepermanently connected via a hermetic seal without the need for anintermediary connector block.

FIG. 3 is a line drawing of the front view of the human head of FIG. 1,further showing by way of example the locations of the two prior art DBSelectrodes 20 and 20′.

FIG. 4 illustrates the quadpolar electrodes 30 of the deep brainelectrode 20, and also the associated multi-wire electrical lead 22that, as previously mentioned, is routed between the skin 32 and theskull 34. A burr hole 36 is typically formed through the skull 34 togain access for implantation of the DBS electrode assembly 20.

There are a number of problems associated with the prior art illustratedin FIGS. 1-4. One is the difficulty, due to the length of the leads 22and 22′, in routing the leads 22 and 22′ from the pectorally implantedpulse generators 26 and 26′ across the pectoral area of the chest, upthe side of the neck and the back of the skull, and then finally down tothe DBS electrodes 20 and 20′. Associated problems include the tendencyfor there to be infections, reliability issues due to lead breakageassociated with the constant twisting, turning and bending of the headand neck area, as well as the fact that it has been well demonstratedthat long leads can be problematic during medical diagnostic procedures,such as magnetic resonance imaging (MRI), U.S. Pat. No. 7,363,090 andU.S. Patent Publication Nos. 2007-0112398 A1, 2008-0071313 A1,2008-0049376 A1, 2008-0132987 A1, 2008-0116997 A1, and 2008-0161886A1are all incorporated herein by reference for an understanding of how theelectromagnetic fields from MRI couple to implanted leads and can causeassociated overheating and thermal injury.

There are also a number of problems associated with the surgicalprocedure involving tunneling of the leads under the skin and overtorturous bends and surfaces. Not only are there issues of infection,the tunneling tools sometimes cause injury or poke through the skin andhave other deleterious effects.

Moreover, there are general electromagnetic interference (EMI) problemsassociated with prior art implanted brain pulse generators or brainstimulators that also do sensing. The long leads 22 and 22′ act asantennas and pick up stray electromagnetic signals from the patientenvironment. For example, electromagnetic emitters such as cellulartelephones, microwave ovens, RFID readers and the like, can all inducesignals on these leads which can disrupt the proper operation of theimplanted pulse generator and/or its sensing signals.

There are additional problems associated with the relatively longelectrical leads 22 and 22′ that run from the implanted pulse generators26 and 26′ up to the location of the subdural electrodes 24′ and the DBSelectrodes 20 and 20′, FIG. 5 is a top view of a sketch from an actualMRI slice taken through a patient's skull. In this case the MRI scanningof the patient was inadvertent. That is, the radiology technician wasnot aware of the presence of the deep brain stimulator. One can see anarea 38 of a severe brain lesion that was caused by thermal injuryduring this 1.5 Tesla MRI procedure. This is a dramatic illustration ofhow the pulsed RF field produced by MRI equipment can overheat longimplanted leads and how sensitive the brain is to thermal injury. Thispatient experienced severe neurologic disabilities due to this traumaticinjury.

Accordingly, there is a need to eliminate, as much as possible, theassociated lead wiring that runs from the implanted pulse generators 26and 26′ up to the location of the DBS electrodes 20 and 20′. The presentinvention addresses this need and provides other related advantages.

SUMMARY OF THE INVENTION

The present invention relates to a satellite therapy delivery system forbrain neuromodulation which comprises, generally, a control modulehaving an RF transmitter or transceiver, and a satellite brainstimulation and/or sensing (SBS) module including biologic stimulatingand/or sensing electrodes, a power source, and an RF receiver ortransceiver for wireless communication with the control module. Thecontrol module may be implanted within a patient's body at a locationremote from the SBS module, or it may be externally worn by a patienthaving an implanted SBS module. The stimulating and/or sensingelectrodes of the SBS module include a deep brain electrode, orsubcutaneous or subdural paddle, patch or pad electrodes.

The control module and the SBS module may operate in an open loopcommunication mode or in a closed loop communication mode. The SBSmodule may comprise a plurality of SBS modules, each capable ofindependent wireless communication with the control module. Moreover,the SBS modules may be configured for independent wireless communicationwith each other.

The control module typically includes telemetry for wirelesslycommunicating with an external programmer or network to permittransmission of patient data which may include, for example, GPS data,current or historical sensed patient biologic data, or current orhistorical therapy delivery data.

The SBS module typically comprises a pulse generator and a power source.A bandstop filter may be associated with the stimulating and/or sensingelectrodes or their associated leads. The SBS module further includes aprocessing circuit which is electrically coupled to the SBS module RFreceiver or transceiver, and the power source. The processing circuitmay include a protection diode array, and actuates the stimulatingelectrodes in response to a signal received from the control module. Ina closed loop communication mode, the SBS module transmits sensedbiologic data to the control module, the control module processes suchbiologic data to determine if therapy is required, and if therapy isrequired, the control module transmits actuation instructions to the SBSmodule. Such transmitted instructions include stimulation electrodeactuation timing and wave shape instructions. The SBS module maytransmit sensed biologic data to the control module at regularintermittent intervals, or only when pre-defined biologic data isdetected.

Moreover, the SBS module comprises a biocompatible and hermeticallysealed housing. The housing itself comprises a body, a removable cap,and a biocompatible O-ring having a leak rate of no more than 10⁻⁸ cubiccentimeters per second. The SBS housing body is fixed within a burr-holethrough a patient's skull. Preferably, the cap of the SBS module housingis disposed generally coplanar with an outer surface of the patient'sskull. A skin flap overlies the cap over the SBS module housing, whichcan be easily removed to gain access to the cap and, upon removal of thecap, to a battery within the housing. The SBS housing may be fixed tothe patient's skull utilizing screws to prevent twisting of the SBShousing when the cap is removed. Moreover, the SBS module housingincludes fixation tabs disposed within corresponding burr-hole recesses.

The SBS module housing may comprise a ceramic housing, and preferably analumina ceramic housing. In this case, the leads for the electrodesand/or an antenna may extend directly through the housing without therequirement for a hermetic terminal. If the SBS housing is made of amore traditional biocompatible metal, a hermetic terminal is providedthrough which the antenna and/or leads for the electrodes extend.

A circuit board is disposed within the SBS housing, which includes areceiver or transceiver portion, and the circuit board is electricallycoupled to the power source, the electrodes and an RF antenna. Aprotection diode array may be electronically coupled to the circuitboard and/or the RF antenna. As discussed below, one or more of theelectrodes may serve as the RF antenna.

In alternate embodiments, the SBS housing may include an exteriorreceptacle for an electrode lead plug. This permits electrical couplingbetween the electrode lead and the circuit board through the SBShousing.

The power source for the SBS module preferably comprises a replaceablebattery module which is sealed within a biocompatible and hermeticallysealed enclosure. This hermetically sealed battery module is itselfdisposed within the biocompatible and hermetically sealed housing of theSBS module.

Other features and advantages of the present invention will becomeapparent from the following more detailed description, taken inconjunction with the accompanying drawings which illustrate, by way ofexample, principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a side view of a human skull with two guadpolar brainstimulation electrodes placed deeply into the brain matter;

FIG. 2 is an X-ray tracing of the front view of the pectoral area of thesame patient shown in FIG. 1, showing two implantable pulse generators;

FIG. 3 is a line drawing of the front view of a human face showing twoimplanted prior art deep brain electrodes;

FIG. 4 is an enlarged fragmented sectional view of the area indicated bythe line 1 in FIG. 3;

FIG. 5 is a top view of an MRI slice taken through a patient's skullthat had a deep brain electrode implanted during an MRI procedure, andspecifically showing an area of severe brain lesion caused by thermalinjury;

FIG. 6 is an outline drawing of a human head and torso, illustrating asatellite therapy delivery system incorporating the principles of thepresent invention;

FIG. 7 is an enlarged perspective view of one of the satellite brainstimulation and/or sensing neuromodulation (SBS) modules of FIG. 6;

FIG. 8 is a perspective view illustrating an alternative using for theSBS module of FIG. 7;

FIG. 9 is a plan view of a portion of a patient's skull illustrating thefirst step of a process for fitting the SBS modules of FIGS. 7 and 8;

FIG. 10 is a view similar to FIG. 9, illustrating a subsequent step forpreparing the skull for the remote SBS modules of FIGS. 7 and 8;

FIG. 11 is a cross-sectional view of the stepped burr hole createdfollowing the steps of FIGS. 9 and 10;

FIG. 12 is a plan view illustrating the finished stepped burr hole ofFIG. 11;

FIG. 13 is an enlarged, exploded sectional view taken generally alongthe line 13-13 of FIG. 7;

FIG. 14 is a view similar to FIGS. 7 and 13, illustrating an alternativeembodiment of a remote SBS module;

FIG. 15 illustrates an alternative embodiment similar to FIG. 14; and

FIG. 16 is a block diagram of a control and telemetry system for theremote SBS module of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a satellite therapy delivery systemfor brain neuromodulation which effectively eliminates, as much aspossible, the lead wiring that runs from the implanted pulse generatorto the location of the brain stimulation and/or sensing electrodes.FIGS. 6 through 16 illustrate various apparatus and procedures foraccomplishing the present invention. Also disclosed is a novelimplantation approach for satellite brain stimulation module(s) whichallows for multiple battery replacements without removing thestimulation module(s) or its associated electrodes. Battery replacementis as simple as injection of a local anesthetic and then incising andlifting a skull skin flap and then unscrewing or snapping open ahermetically sealed battery compartment.

FIG. 6 is an outline drawing of a human head 40 and torso 42. Thesatellite therapy delivery system of the present invention comprises acontrol module 44 that is typically implanted in the pectoral region ina manner very similar to a cardiac pacemaker or an implantabledefibrillator. It can be implanted just under the skin, under the fattylayers or even under the pectoral muscle. In general, it will be housedin a titanium can 46 to protect its delicate electronic circuitry andbattery from body fluids and moisture. The hermetically sealed can 46also prevents any toxic materials that are associated with theelectronic circuit board(s) or battery to leech out and contaminate bodytissue. A unipolar or bipolar hermetic seal 48 is provided through whicha conductive lead 50 extends. The purpose of this lead 50 is to providean external antenna for transmission and reception of radio frequency(RF) pulses in accordance with the satellite pacing principles of thepresent invention. It will be appreciated that the implanted controlmodule 44 could be placed at any other location that is convenient inthe body, such as in the back or in the abdomen. The control module 44could also be placed in a thicker area in the skull, for example, abovethe ear, or in another location in the skull or in any other area ofthick bone (for example, the iliac crest). It could even be externallybelt worn 44′ in certain applications. The belt worn control module 44′could also be placed anywhere else on the body, for example, in a handbag worn over the shoulder and so forth. It could even be placed on atable or a bedside night stand near the patient. It would be desirable,in some cases, that the externally worn control module 44 be waterresistant. In this case, it wouldn't need to be totally hermeticallysealed since it is not placed inside the body where it would be directlyand continuously exposed to body fluids. However, if it were belt wornand was hermetically sealed, one could even go swimming with it.

Satellite brain stimulating and/or sensing (SBS) modules 52 and 52′ areshown connected to and include quadpolar deep brain electrode assemblies30 and 30′. These deep brain electrode assemblies 30 and 30′ can alsoact as RF antennas which can transmit and receive RF energy to and fromthe control module 44. Accordingly, there is an RF telemetry link thatis established between the implanted control module 44 and the SBSmodules 52 and 52′.

The SBS modules 52 and 52′ preferably contain their own power source(battery). Alternatively, they can capture energy by energy harvestingusing chemical, thermal or external magnetic fields in a storagecapacitor. In the simplest embodiment, the SBS modules 52 and 52′ aretriggered by RE pulses containing electronic instructions transmitted bythe control module 44. The control module 44 and the SBS modules 52 and52′ form an RE telemetry subsystem that provides the wirelessinfrastructure needed to communicate measurement and control data withinthe human body. All nodes (44, 52 and 52′) within the same system(implantable wireless network) are paired during a commissioning processwhereby an association is made between nodes. What this means is thatcertain RE signals that are transmitted by the control module 44 areonly received and processed by the SBS module 52 and other signals havea hand shake and are only received and processed by the SBS module 52′.Data communicated (messages) in this system are encrypted using a keythat is common to all nodes in the same system, and is unique to eachsystem. This makes the system inherently highly resistant or robustagainst electromagnetic interference from other outside electromagneticsignals. In other words, only an RF signal that has the correct encodingwill be capable of triggering pulses in the SBS modules 52 and 52′.Messages in the system originate from a source node which can be eitherthe control module 44 or either of the SBS modules 52 or 52′, andterminate at a destination node. Some or all nodes may containintermediary features that relay messages in one or more alternaterouting patterns. In the preferred embodiment, the multiway routingcapability provides redundancy needed for increased reliability. It willbe apparent to those skilled in the art that this same system can bekeyed to other satellite modules placed anywhere within the human body,such as for a spinal cord stimulator.

There are a number of frequencies that can be used for the RF telemetrysubsystem. One is the designated medical implant communication service(MICS) frequency band. This band is from 402-405 MHz and is availablefor MICS operations on a shared, secondary basis. The FederalCommunications Commission (FCC) determined that, compared to otheravailable frequencies, the 402-405 MHz frequency band best meets thetechnical requirements for a number of reasons. First of all, the402-405 MHz frequencies have propagation characteristics conducive tothe transmission of radio signals within the human body. In addition,equipment designed to operate in the MICS band satisfies the requirementfor human implant with respect to size, power, antenna performance, andreceiver design. Furthermore, the MICS band is compatible withinternational frequency allocations. Moreover, the use of the MICSfrequency band does not pose a significant risk of interference to otherradio operations in that band. Finally, operation of MICS band ispermitted by rule and without the need for individual license as issuedby the FCC. For all these reasons, the MICS band is preferred for use inthe present invention, although many other frequencies would also besuitable. The FCC is now considering a new RF frequency band that willbe dedicated only to medical implants that will offer additionalbandwidth. If this new frequency band is adopted, it will become the newpreferred operating frequency band of the present invention.

The control module 44 has a number of very important features. First ofall, being relatively larger than the relatively small SBS modules 52and 52′, it can have a much larger long-life power source (battery). Itsbattery can have primary battery chemistries that are common forimplantable devices, such as lithium-iodine, lithium carbon monofloride,lithium-silver vanadium pentoxide, lithium manganese dioxide and thelike. Secondary batteries (rechargeable) technologies can also be used,including but not limited to lithium-ion or other power storage devices,such as ultra capacitors or equivalent high-energy storage capacitorsand the like.

For an externally worn device control module 44, alternate and lessexpensive battery technologies can also be used. These are commonlyavailable in the consumer marketplace and include alkaline batteries,nickel metal hydride, NiCad, gel cells, carbon monofloride and manganesedioxide and liquid catho systems, including thionyl-chloride andsulfuryl-chloride. In addition, if the external control module 44 wereworn in an appropriate location (for example, on the wrist or theankle), various energy harvesting techniques could be used that dependupon the motion of the human body, such as mechanical energy harvesting,piezoelectric type mechanisms, or electromagnetic induction.

In addition to being belt worn, the external control module can also beworn as a type of necklace, a bracelet, an iPod-type holder on an armband, in a vest, in a type of knapsack or backpack, or the like. Thecontrol module 44′ could even be sitting on a desk, nightstand or atable next to the patient. The primary consideration here is that theexternally worn control module 44′ be close enough (within RFtelecommunication range) to properly communicate with, and in apreferred embodiment create a closed loop communication system with, theremote SBS modules 52 and 52′. In the case where the external controlmodule 44′ has a secondary (rechargeable) battery, in addition toproviding its communication functions whether sitting on a desk ortable, it could also be conveniently recharged by being plugged into awall charger, a solar type charger, or one that depends on movement ormotion. In a preferred embodiment, one would have a convenient module ontheir stand that is plugged into the wall at all times with a convenientreceptacle similar to those used for remote telephones when they areplugged in to their cradle to be recharged. Another advantage of theexternally worn control module 44′ is it can be fitted with controlsthat the patient can adjust. For example, for a patient that has acertain seizure, pain or tremor situation, he or she could control anadjustment knob or digital input (not shown) on the control module 44′thereby controlling the level of therapy. These various controls couldalso adjust the type of pulse, whether it be triangular, square wave,trapezoidal, rectangular, or other pulse shapes, the pulse repetitionrate, and the like, that is being delivered to the electrodes 30 by theremote SBS modules 52 and 52′. For implanted control modules 44, thephysician or patent can still communicate and adjust therapy via a closecoupled (wanded telemetry) or a distant RF telemetry link.

The SBS modules 52 and 52′ can each be either just a receiver and pulsegenerator, meaning that it will deliver pulses when instructed by thecontrol module 44 (an open loop communication system), or, preferably,the SBS modules 52 and 52′ will include transceivers to create a closedloop communication system with the controller module 44, which shallalso have an RF transceiver. In other words, the satellite therapydelivery system of the present invention has two primary communicationmodes. In the open loop communication mode, the SBS module 52 does notdo any sensing of brain electrical activity. The control module 44 ispre-programmed so that it sends controlled timing pulses to the SBSmodules 52 and 52′. In an improved embodiment, the timing pulses wouldbe preceded or include waveshape information so that the wave shapegenerator that is part of the SBS module 52 and/or 52′ could produce thedesired waveform and pulse amplitudes. The waveform information wouldalso be encoded or incorporate a look-up table so the SBS module 52and/or 52′ could select, between whether or not to deliver a sinusoidalpulse, a triangular pulse, a square wave or any other type of waveform.In the open loop communication mode, the SBS modules 52 and 52′ aresimply waveform generators that receive their timing and waveform typeinformation from the control module 44. In the preferred closed loopcommunication mode, the SBS modules 52 and 52′ continuously orintermittently sense brain wave activity and can detect the onset of anelectrical storm which often precedes a seizure. These electrical stormshave variable frequency content and amplitudes. The SBS modules 52 and32′ would transmit this data to the control module 44. The controlmodule 44, in the closed loop communication mode, embodiesmicroprocessors and software algorithms that analyze the brain activitythat is being transmitted from the SBS modules 52 and 52′. If thesoftware algorithm indicates that a seizure or other inappropriateelectrical brain activity is occurring, then the microprocessors andsoftware make a decision for the most appropriate amplitude andwaveshape of the therapy pulses. The control module 44 then selects theappropriate therapy pulse waveshape, pulse repetition rates and period(timing), and sends that information via the RF communication link tothe SBS modules 52 and/or 52′. The SBS modules 52 and 52′ would thendeliver the appropriate therapy and again monitor brain electricalactivities to see if additional therapy is needed. FIG. 6 shows a closedloop communication system wherein the control module 44 can receive RFsignals 54 from the SBS modules 52 and 52′ transmitted as an RF pulse56. When the control module 44 determines that there is inappropriatebrain electrical activity, it transmits an RF instruction pulse 58 whichis received as an RF input 60 to the SBS modules 52 and 52′.

The remote SBS modules 52 and 52′ as shown in the drawings are onlyillustrative of a pair of deep brain stimulators. It will be appreciatedthat any number and various types of SBS modules can be paired with thecontrol module 44 in accordance with the present invention. Referringonce again to FIG. 6, in closed loop communication mode, deep brainsignals or other biological brain signals that are sensed by the SBSmodules 52 and 52′ are transmitted by the RF telemetry link 56 to thecontrol module 44. These signals can be, in turn, transmitted to anexternal network such as a master control center, a hospital diagnosticcenter or even a physician's office for analysis or diagnosis. Thecontrol modules 44 or 44′ can be close coupled with a telemetry wand orRF telemetry antenna so that an external programmer 62 can be used toreprogram the control unit 44 or 44′. The external programmer 62 canalso be used to store other information such as battery status, pastbrain electrical activity events and the like. In addition, the externalprogrammer 62 monitors the system for malfunctions such as electrical,programming or any other faults. These errors are displayed alerting thepatient or caregiver of any problems. In addition, such error codescould also be transmitted as a telemetric signal. These telemetrysignals could also be transmitted or coupled to telephone lines or linksand can even be provided to existing cellular telephone networks orcommunication systems all, for the purposes of remote monitoring, remoteprogramming and remote diagnostics by appropriate medical personnel. Thecontrol modules 44 or 44′ could also be outfitted with a GPS locatorsuch that if the patient was having a traumatic medical event, thepatient could be located and emergency medical personnel could beappropriately dispatched.

The present invention is not limited to just the stimulation and sensingof electrical signals. The remote SBS modules 52 and 52′ can also beused to sense patent biologic data including cranial pressures andtransmit that information back to the control module 44 or 44′ as wellas cerebrospinal fluid pressures (normal hydrocephalus). In other words,the present invention encompasses all aspects of continuous patientbrain status and monitoring. Even real-time pulse oximetry or bloodpressure monitoring can also be integrated into this overall system.

The SBS modules 52 and 52′ can even be externally powered if desired.The power would be supplied by an external electromagnetic source thatwould couple with an internal antenna similar to an RFID chip therebyproviding energy to supply the stimulation pulse. Alternatively, theexternal energy source could provide RE energy to recharge a battery orto recharge an energy storage capacitor. This is more fully described inU.S. Pat. No. 6,615,074, the contents of which are incorporated herein.

FIG. 7 illustrates another preferred embodiment of one of the SBSmodules 52. The SBS module 52 is designed to be slipped into a closefitting skull burr hole 36. The SBS module 52 comprises, generally, abiocompatible and hermetically sealed housing 64 comprised of a body 66and a removable cap 68. Disposed within the housing 64 is a power source(shown as a battery 70 in FIG. 13) and an RF receiver or transceivercircuit 72 (FIG. 16) for wireless communication with the control module44 or 44′. A bundle of leadwires 74 extend through the body 66 of thehousing 64 and terminate at the quadpolar electrodes 30. The body 66 isfurther provided with a pair of tabs 76 which each may be provided withan aperture 78 therethrough (FIG. 7), or without such an aperture asillustrated in FIG. 8. The aperture 78 is provided to accommodate askull fixation screw 80 which is utilized to help secure the housing 64in place relative to the skull 34 and prevent twisting thereof duringremoval of the cap 68 from the body 66. In this regard, the cap 68 isprovided with a pair or recessed slots 82 and 82′.

In the alternate embodiment of the housing 64 shown in FIG. 8, theapertures 78 through the tabs 76 for the screws 80 have been omitted.There may be instances where use of skull fixation screws 80 would beundesirable. In this case, the tabs 76 would be located withincorresponding recesses 84 in the skull 34 adjacent to the formedburr-hole 36 to resist or prevent twisting of the housing body 66 whenthe cap 68 is screwed onto or unscrewed from the body 66.

Referring to FIGS. 9-12, the skull burr-hole 36 would typically beformed by first drilling two shallow recesses 86 and 86′, and then agenerally circular burr-hole 36 would be drilled through the skull 34between and through a portion of each of the recesses 86 and 86′ (FIGS.9 and 10). The resultant stepped burr-hole 36 includes a passageway allthe way through the skull 34 and a step or shoulder forming the recesses84 which are configured to receive the tabs 76 of the SMS module housing64 (see FIGS. 11 and 12). The SBS modules 52 and 52′ are implanted intothe skull 34 by first creating an incision in the tissue overlaying theskull to form a flap. This flap, usually with hair included, is flippedback to expose the skull. Once the SBS module 52 or 52′ is affixed andits associated electrodes are implanted, the skin flap is set back inplace and sutured. In a short time the suture heals. When the battery 70needs replacement, all that is needed is a simple injection ofanesthetic such as Xylocalne and a new skin flap is created to exposethe cap 68. Replacing the battery 70 is as simple as removing the cap 68and installing a new battery. It is preferable to install a new O-ring94 and new cap 68 at each battery replacement interval to minimize therisk of complications such as infection. Battery replacement intervalsvary from a few months to several years depending on the frequency ofthe need for therapy delivery and the amplitude and type of waveformneeded.

FIG. 13 is a cross-sectional view taken generally along the line 13-13from FIG. 7. The cap 68 is shown removed from the body 66 of the housing64. The upper surface of the cap 68 includes the slots 82 and 82′ thatare used to facilitate removal of the cap 68 from the body 66. Theperiphery of the cap 68 adjacent to a lower surface has threads 88configured for mating reception with internal threads 90 defining a capreceiving recess 92 adjacent to an upper surface of the body 66. TheO-ring 94 is disposed within the body 66 so that as the cap 68 isscrewed into the cap receiving recess 92, a lower surface of the capengages the O-ring 94 to form a hermetic seal between the cap 68 and thebody 66.

With regard to the cap 68, it will be appreciated that the slots 82 and82′ could take a variety of shapes including a single slot, foraccommodating a flat-tip screwdriver in the center of the cap, or anyother shape, for example, a slot that could accommodate a cross-tipscrewdriver. An important point is that the cap 68 firmly mate with thetool such that a suitable torque may be applied to unscrew the cap 68from the body 66 and reseat it. In this regard, it is desirable that thetools utilized have torque wrench-like properties so that when the cap68 is seated within the cap receiving recess 92, a proper compressionforce is applied to the O-ring 94.

Disposed within the body 66 is a circuit substrate 96 which contains theRF transceiver circuitry 72 (FIG. 16) and the pulse forming network forstimulating the electrodes 30. The control module 44 would make thedecision as to which electrodes 30 or electrode pairs to stimulate,including electrical vectors between the SBS modules 52 and 52′, and thelike. Electrical vectors can also be generated betweensubcutaneous/subdural electrodes 24, or between DBS electrodes 20, aswill be later described. As shown, the battery 70 is also disposedwithin the body 66 of the housing 64.

It is important that the O-ring 94 be of a suitable silicone, PTFE,elastomer, fluorocarbon, metal or other long-term biocompatiblecompressible material such that long-term hermeticity is maintained. Thereason for this is for convenient replacement of the battery 70 atregular intervals. Of course, this would only be needed if the battery70 were a primary battery and could not be recharged. The biocompatibleO-ring 94 preferably has a leak rate of no more than 10⁻⁸ cubiccentimeters per second. The O-ring 94 may be seated under a screw-in cap68 as illustrated or the cap may be snapped in against a cam (not shown)and then later pried off for battery replacement. The screw-in versionis the preferred embodiment. The physician battery replacement kit wouldinclude instructions and illustrations to the physician as how to locateand form the skin flap. This kit would also include a torque tool and anew cap 68 and O-ring 94. The torque tool is important to assure thatthe O-ring 94 is properly seated. An adjunct sealant can also be placedaround the cap perimeter or over the entire cap 68 surface to provideadditional sealing and biocompatibility (for example, some patientsreact unfavorably to titanium and may even have allergic reactions). TheO-ring 94 may be replaced or enhanced by a flexible injectable elastomersuch as that described in US 2007-0168032.

In a preferred embodiment, the entire SBS module assembly would be flushwith the top of the skull 34 and would be stitched under a skin flapwith the hair intact. Accordingly, when the battery 70 was to bereplaced, a surgeon would make a simple incision and pull back the skinflap, unscrew the cap 68 and insert a new battery. In an alternativeembodiment, the top of the entire assembly could be exposed above theskull (for example, in a plastic piece or a simple plastic lid) suchthat battery replacement would be more convenient. This would not be asaesthetically pleasing or as comfortable for the patient, but could bean embodiment that would be chosen for elderly people or for example,people confined to convalescent home situations.

The body 66 includes a quad polar hermetic terminal 98 with fourleadwires 74 that are routed down to the distal electrodes 30. The extraamount of these leadwires 74 can be spaced backwards and forwardsunderneath the remote SBS module housing 64. This is so that the depthof the electrodes 30 into the brain tissue can be precisely maintainedand that any excess leadwire 74 can be wrapped up in the subdural area.In a preferred embodiment, the leadwires 74 are wrapped randomly or infigure eight patterns such that they not, form an efficient couplingloop for external electromagnetic field emitters (such as MRI).

Also shown is an optional RF antenna 100 coming through a secondhermetic terminal 102. It will be understood that this antenna 100 couldalso be accommodated by the leadwire hermetic terminal 98. The RFantenna 100 can also be one of the leadwires 74 going to the electrodes30. In fact, in a preferred embodiment, the RF antenna 100 is notneeded. This is because the pacing and sensing pulses are in the lowfrequency biological range (0 to 2000 HZ). Accordingly, it is possibleto superimpose on the leadwires 74 high frequency RF signals (forexample, those in the 400 MHz range). In other words, the electrodes 30and leadwires 74 can also simultaneously act as the RF transmittingand/or receiving antenna of the SBS modules 52 and 52′ of the presentinvention.

The circuit substrate 96 includes RF receiving and RF transmittingcircuits. When these circuits operate in conjunction with the RF antenna100, this forms what is known as an RF transceiver. An RF transceiver isrequired for the closed loop communication mode. In the open loopcommunication mode, the circuit substrate 96 would have an RF receiveronly and the pulse forming network would be responsive to controlsignals from the control module 44. In the closed loop communicationmode/embodiment, the transceiver of the SBS module 52 would communicatewith the transceiver of the control module 44 such that electrical brainwave activity is monitored and appropriate therapy is selected.

FIG. 13 also shows an optional bandstop filter module 104. This could beplaced in series with each leadwire 74 to act as a very high impedanceat the selected frequencies of certain medical diagnostic equipment. Inparticular, during magnetic resonancing procedures, the leads andelectrodes are exposed to a very powerful pulsed RF field. By properlyselecting the values of inductance and capacitance, one can cause thecircuit to be resonant at the pulsed resonant frequency of an MRIsystem. This would create a very high impedance at that frequency andthereby stop the flow of current into the leadwires 74. It would alsoact as a very important protection to the microelectronics located onthe circuit substrate 96. The bandstop filter 104 could be replaced byelectronic switches, MEMs switches, multiplexers or a short to housing.Also provided are diode protection arrays 106 (FIG. 16) to protect thecircuit electronics from over-voltages caused by the patient coming intocontact with electrostatic discharges, automatic external defibrillators(AEDs), and the like. See U.S. Pat. No. 7,363,090 and U.S. PatentPublication Nos. 2007-0112398 A1, 2008-0071313 A1, 2008-0049376 A1,2008-0132987 A1, 2008-0116997 A1, and 2008-0161886 A1, the contents ofall of which are incorporated herein by reference.

The circuit substrate 96 could be a rigid substrate consisting ofalumina ceramic, FR-4 board, or even a flexible substrate. A preferredembodiment would be to use a polyimide flex substrate designed forrobotic placement and manufacturing of components. The automatedmanufacturing system would be fed from tape and reel components whereinpick-and-place robots would place the components which then go throughan automated wave soldering operation followed by a cleaning operationthen by an automated microscopic optical tolerance position measurement(quality control), followed by automated electrical measurements.

The entire housing 64 could either be of a biocompatible material suchas titanium, platinum or other suitable biocompatible metal. Pressedpowder metallurgy, machining techniques or the like can be used to formthese shapes. The housing 64 could also be of a high fired or low firedceramic construction such as nearly pure alumina ceramic. The processwould involve tools (fixtures) into which powdered alumina would bepressed. Then the shapes would be fired at high temperature so that theceramic is sintered into a hard body. Leads could either be co-fired orlater gold brazed into lead penetration holes. This eliminates the needfor separate hermetic terminals 98 and 102. The interior of the ceramicbody could be metalized with a thin coating of metal to provide suitableelectromagnetic interference shielding and protection.

FIG. 14 illustrates an alternative embodiment of an SBS module 52. Onecan see that there is a pair of DBS electrodes 20 and 20′. These areboth connected to a single SBS module 52 as shown. Also shown are remotepaddle electrodes 24 and 24′. These would be typically placed betweenthe skin and the skull or even under the skull. The purpose of this isso that the implanting physician has a number of options as to vectorsfor sensing brain activity or vectors for providing brain stimulationpulses. In other words, one could stimulate or sense between any of theelectrode pairs 30 or 30′ or between, for example, the DBS electrode 20and the paddle electrode 24, or even between the individual electrodes30 of the DBS electrode 20. Likewise, one could stimulate or sensebetween any of the individual electrodes 108 of the paddle electrode24′.

FIG. 15 illustrates another alternative embodiment of the presentinvention. The SBS module 52 consists of a titanium or alumina housing64 with two connector block assemblies 110, 110′. The connector blockassemblies 110 and 110′ each have an inline receptacle 112 that is verysimilar to pacemaker standard International Standards Organization (ISO)IS-4. Also shown are IS-4 type proximal mating plugs 114 and 114′ whichare attached to leads 74 and 74′ and then to a DBS electrode assembly inaccordance with the present invention. The advantage of the structure ofFIG. 15 is that the entire SBS module 52 can be placed into a speciallyformed skull burr hole 36 and then leads 74 and 74′ can be routed insuch a way to provide the stimulus into brain tissue as required. Oncethe primary battery was depleted or the electronics failed in the SBSmodule 52, it could be removed and a new one could simply be pluggedinto the existing leads 74 and 74′. This is a relatively easy procedurecompared to the extremely invasive procedure that would be required toremove the DBS electrodes 20 and 20′ which could result in brain tissuetrauma. However, the burr hole 36 would be very complicated and wouldrequire a great deal of milling and machining. In other words, it is nota simple drilling operation of round holes using bore fixtures as shownin FIGS. 9-12.

FIG. 16 is a block diagram of a control and telemetry system of theclosed loop embodiment of the SBS module 52. The circuit board 96 willhave a RF transceiver circuit 72, an RF module 116, a signal processingcircuit 118, and a pulse generator circuit 120 capable of producingvarious pulse shapes and repetition rates. This transceiver circuit 72is designed to send and receive RF signals that are modulated tocommunicate with the control module 44. Not shown are capacitors inseries with each electrode to prevent any DC bias from being conductedfrom the circuit boards to human tissue. The RF signals, in a preferredembodiment, are digitally modulated or frequency shift keyed in order tobe able to transmit sensed brain wave information from the SBS module 52to the control module 44. In turn, similar modulation is used for the RFsignals that are transmitted by the control module 44 to control thewave shape and repetition rate that is delivered to the brain electrodesby the SBS module 52. Since the SBS module 52 is preferably very smallin size, it will have very limited microprocessor capability. In apreferred embodiment, in its architecture would be stored a look-uptable. In this way, a simple lettered digital code could be receivedfrom the main control module 44. For example, if an alpha numeric A12was received by the SBS module 52, its look-up table would tell it todeliver, for example, a triangular pulse sequence with a repetition rateof 10 beats per minute and an amplitude of 4 millivolts. By havinglook-up tables stored into hard memory, one not only greatly decreasesthe amount of memory in software that must be contained within the SBSmodule 52, but one also saves significant battery life. The reason forthis is that the RF transmission bursts can be very short as compared tosending a lot of information, such as sending exact pulse shape andtiming information. A storage capacitor 122 is further provided so thata sufficient stimulation pulse may be generated on command as requiredby the control module 44. As mentioned previously, protection diodearrays 106 may also be provided.

From the foregoing, it will be appreciated that the satellite therapydelivery system for brain neuromodulation comprises a control moduleincluding an RF transmitter or transceiver, and a satellite brainstimulation and/or sensing (SBS) module including biologic stimulatingand/or sensing electrodes, a power source, and an RF receiver ortransceiver for wireless communication with the control module. Thecontrol module 44 may be implanted within a patient's body at a locationremote from the SBS modules 52 and 52′, or it may be externally worn bythe patient. The stimulating and/or sensing electrodes of the SBSmodules 52 and 52′ may include DBS electrodes 20 and 20′, and/orsubcutaneous or subdural paddle, patch or pad electrodes 24 and 24′. TheSBS modules 52 and 52′ comprise biocompatible and hermetic sealedhousings preferably fixed within a burr-hole through a patient's skull.The satellite therapy delivery system of the present invention lendsitself to both open loop communication between the control module 44 andthe satellite modules 52 and 52′, and closed loop communication betweenthose same components. Advantageously, the housing 64 for the SBSmodules 52 and 52′ includes a removable cap 68 which permits easy accessto a battery 70 normally disposed therein.

Although several particular embodiments of the invention have beendescribed in detail for purposes of illustration, various modificationsmay be made without departing from the spirit and scope of theinvention. Accordingly, the invention is not to be limited, except bythe appended claims.

What is claimed is:
 1. A satellite therapy delivery system for brainneuromodulation, comprising: a) a satellite brain stimulation and/orsensing (SBS) module comprising: i) at least one biologic stimulatingand/or sensing electrode; ii) an SBS housing; iii) a first electricalpower source disposed within the SBS housing, and a first RF transceiverfor RF wireless communication with a control module; and iv) aprocessing circuit electrically connected to the first RF transceiver,and the first electrical power source; b) the control module, capable ofanalyzing an SBS RF wireless signal module, comprising: i) a controlmodule housing; ii) a second electrical power source; iii) a second RFtransceiver and a microprocessor; and iv) the second RF transceiver andthe microprocessor being electrically connectable to the secondelectrical power source positioned within the control module housing; c)the SBS housing is positionable within a burr hole through a patient'sskull; and d) wherein the biologic stimulating and/or sensing electrodeis actuatable by the SBS processing circuit in response to an RFwireless signal having been received from the control module, thecontrol module RF wireless signal having been firstly received by theSBS module and secondly analyzed by the control module.
 2. The system ofclaim 1, wherein the control module is not implanted within a skull of apatient.
 3. The system of claim 1, wherein the control module isconfigurable to be externally worn by a patient having an implanted SBSmodule.
 4. The system of claim 1, wherein the stimulating and/or sensingelectrode of the SBS module is selected from the group consisting of adeep brain electrode, and a subcutaneous or subdural paddle, patch orpad electrode.
 5. The system of claim 1, wherein the control module andthe SBS module are configurable to operate in an open loop communicationmode.
 6. The system of claim 1, wherein the control module and the SBSmodule are configurable to operate in a closed loop communication mode.7. The system of claim 1, wherein the SBS module comprises a pluralityof SBS modules, each configurable to communicate independently with thecontrol module through wireless communication.
 8. The system of claim 7,wherein the SBS modules are configurable to communicate independentlywith each other through wireless communication.
 9. The system of claim1, wherein the SBS module comprises a pulse generator.
 10. The system ofclaim 1, wherein the control module is configurable to communicate withan external programmer or network through telemetric wirelesscommunication.
 11. The system of claim 10, wherein the control module iscapable of permitting telemetric transmission of patient data theexternal programmer or network.
 13. The system of claim 12, wherein thetransmitted patient data is selected from the group consisting of GPSdata, current or historical-sensed patient biologic data, and current orhistorical therapy delivery data.
 14. The system of claim 1, whereinactuation of the stimulating electrodes occurs by the processing circuitin response to a signal received from the control module.
 15. The systemof claim 1, wherein the SBS module is configurable to transmit sensedbiologic data to the control module, and the control module isconfigurable to process biologic data to determine if therapy isrequired, and wherein when therapy is required, actuation instructionsare transmittable by the control module to the SBS module.
 16. Thesystem of claim 15, wherein the transmittable instructions comprisestimulation electrode actuation timing and waveshape instructions. 17.The system of claim 15, wherein the SBS module is configurable tointermittently transmit the sensed biologic data to the control module.18. The system of claim 17, wherein the SBS module is configurable totransmit the sensed biologic data to the control module only whenpre-defined biologic data is detected by the SBS module.
 19. The systemof claim 1, wherein the SBS housing is fixable to a patient's skullutilizing screws to prevent twisting of the SBS housing body.
 20. Thesystem of claim 1, wherein the SBS housing comprises fixation tabsdisposed within corresponding burr-hole recesses.
 21. The system ofclaim 1, wherein the SBS housing comprises a ceramic housing.
 22. Thesystem of claim 21, wherein the ceramic housing comprises an aluminaceramic housing.
 23. The system of claim 1, wherein a lead for theelectrode and/or an antenna extend through the SBS housing.
 24. Thesystem of claim 1, wherein the SBS housing comprises a hermetic terminalthrough which an antenna extends.
 25. The system of claim 24, whereinthe SBS housing comprises at least one hermetic terminal through which alead for the electrode extends.
 26. The system of claim 1, comprises acircuit board disposed within the SBS housing, the circuit board havingthe first transceiver portion and being electronically connected to thefirst power source, the electrode and an RF antenna.
 27. The system ofclaim 26, wherein at least electrode serves as the RF antenna.
 28. Thesystem of claim 26, wherein the SBS housing comprises an exteriorreceptacle for an electrode lead plug, configurable to permit anelectrical connection between the electrode lead and the circuit boardthrough the SBS housing.
 29. The system of claim 1, wherein the firstelectrical power source and the second electrical power source arereplaceable.